Magnetic tape reading and writing devices, such as tape drives and cassette tape players and recorders, include a magnetic head in contact with tape from a tape supply reel in a tape cassette or cartridge. The tape is fed from the tape supply reel along the magnetic head, which applies a magnetic flux to a layer of oxide to record data and facilitates a varying magnetic field across a gap in the head to playback or receive data from tape with information recorded thereon. Magnetic heads are designed to record and read data only when the tape is moving across the head.
Magnetic tape devices can suffer from a condition known as “stiction” (i.e., static friction), which is used herein to describe a buildup of static friction between the tape and the magnetic head, or other magnetic tape device components, such as tape cleaners. When stiction occurs, the tape is effectively stuck to the magnetic head. Generally, stiction only occurs when motion of the tape is stopped or moving at an extremely slow rate of speed, such as when the magnetic tape device is not in use or the device is between read and write operations. When the tape is in motion, such as during read and write operations, stiction typically does not occur. Without tape motion, the surface tension of any condensed water between the tape and head often induces stiction. Therefore, the occurrence of stiction is commonly dependent upon the temperature, humidity, and surface characteristics of the tape and head. Moreover, because recent developments have introduced tape and magnetic heads made with smoother and higher capacity elements, stiction in magnetic tape devices, particularly tape drives, has become a growing problem.
Several attempts have been made at overcoming the problem of stiction in magnetic tape devices, each with limited success. For example, attempts have been made to modify the surface characteristics of the magnetic head, which can be very expensive to implement. Other attempts include moving the tape in multiple directions to “unstick” the tape and moving the head up and down relative to the tape. The success of these attempts has been limited because each involves application of a force perpendicular to the static friction force, which may increase the likelihood of tearing or damaging the tape.
An additional attempt includes moving portions of the roller assembly (e.g., the inter-tape guidance rollers) away from the magnetic head to physically move the tape out of contact with the head. Such a movable tape roller assembly can be complex, difficult to manufacture, and costly to implement.
A further attempt includes an anti-stiction device designed to prevent stiction from occurring rather than “unsticking” tape after stiction has occurred. The anti-stiction device includes an anti-adhesion unit with a complex configuration of levers, axles, and actuators (e.g., solenoid or motor) that move a slanted displacement lever to displace the tape if stiction is likely to occur. The anti-stiction device is designed to move the tape out of contact with a tape cleaner and only partially out of contact with a magnetic head if an algorithm indicates the speed of the tape is below a minimum tape speed greater than zero. Such an anti-stiction device is quite complex, is expensive to manufacture due to the large amount of material and components used, and requires an inconvenient amount of overhead and controls to operate.
Based on the above, a magnetic tape device configured to reduce, and even eliminate, stiction between the magnetic head and the tape while overcoming one or more of the shortcomings of conventional magnetic tape devices would be desirable.